HIV virology Flashcards
What are mandatory surface antigen tests for pregnant women?
- Syphillis
- HIV
- Hep B
What animal has been identified as the source of HIV infection in humans?
Chimpanzees
Regarding HIV epidemiology in Africa, what are the routes of infection?
- Heterosexual
- Mother-to-child
- Unscreened blood
In Europe what are main routes of contracting HIV?
Sexual
- MSM
- Heterosexual
Injecting drug use
-less common but can be higher in certain areas
What is the more predominant virus worldwide - HIV-1 or HIV-2?
HIV-1
What cells does the HIV virus target before attaching?
> Cells with CD4 on surface (T-helper) lymphocyte
>Cells with certain chemokine receptors
Is HIV a DNA or RNA virus?
RNA. Converted to DNA in cell by reverse transcriptase
What is the group of HIV retroviruses called?
Lentiviruses
For replication, what does the virus need?
> Host cell
>RNA to be transcribed to DNA
What enzyme integrates the viral DNA into the nuclear genome?
Integrase
What enzyme helps produce enzymes needed for maturation of the replicated virus?
Protease
What lab tests are done to diagnose HIV?
Antigen/antibody tests (ELISA assays)
Lab testing to help in managing HIV?
- Viral load
- HIV resistance testing
- Avidity testing
- Subtype determination
- Tropism testing
- Drug levels
What is the diagnostic window? Why is it significant?
Time during which markers for HIV infection are not detectable/before seroconversion. Varies between individuals.
Testing in this time can lead to false negative results
What is measuring viral load useful for?
- Monitor effectiveness of treatment
- Diagnosis in presence of maternal antibody
What is HIV resistance testing used for? (identifying specific mutations conferring resistance to ART drugs)
- Baseline at diagnosis
- Suboptimal treatment response
- Treatment failing
- Changing treatment
What is the use of tropism testing and for drug levels?
Tropism testing - what co-receptor virus uses to enter cell. For CCR5 antagonist use
Drug levels - compliance
Does your work require you to have an HIV test? When may you need one? And when may you need to avoid situations putting you at risk of HIV?
> If work doesn’t need test you don’t need to inform work
If working abroad you may need HIV test
If in healthcare you need to avoid exposure-prone procedures (EPPs)
What happens to viral load and CD4 count when ART treatment is commenced?
Viral load: fall
CD4 count: rise
What are the potential routes of transmission to healthcare workers of blood borne viruses? Give an example of each.
Percutaneous exposure (eg sharp instrument accidentally penetrating skin). At risk of:
- Hep B
- Hep C
- HIV
Mucocutaneous exposure (eg blood splashing into eyes/mouth/broken skin. At risk of: -HIV
Other than blood which other bodily fluids should be handled with precaution?
- CSF
- Pleural/peritoneal/pericardial fluid
- Breast milk
- Amniotic fluid
- Vaginal secretions/semen
- Saliva
Can corpses be infected with HIV?
Yes - may be for days after death. Avoid leaking of body fluids
What actions should be done after body fluid exposure?
> Wash off splashes on skin with soap and running water
Encourage bleeding if skin broken
Wash out splashes in eye/nose/mouth
REPORT to senior manager or doctor AND to OHS
How is the risk of getting HIV from injury judged?
> Source of contamination
Extent of injury/type of sharp
Likelihood of B/C/HIV in source
Vaccination history
Ideally test source with informed consent
